Joy Stick Shafts

What is a joystick shaft:

The Joystick shaft is the main shaft or level that the player moves to engage different inputs, usually directions in a game.
Usually the shaft is made from metal but plastic has been observed.

Some shafts have the top molded onto the shaft, other shafts are threaded to accept different tops.

Hallow shafts

Some stores, re-distributors and retailers offer hallow or hallow core shafts.
The purpose of Hallow shafts is to allow for wiring such as push buttons on a flight stick or LEDs for a Light up Ball top modification